Air India was forced to ground and fumigate one of its aircraft after rats were spotted scurrying around beneath the seats in the passenger cabin.

The aircraft was flying from Delhi to Calcutta when staff spotted the creatures and raised the alarm to pilots, The Times reported.

Officials say rats on an aircraft pose an extreme danger because they can chew through vital electrical cables, disabling the aircraft’s control systems and leaving pilots unable to steer.

“If that happens, pilots will have no control on any system on board, leading to a disaster,” one Air India official told The Times of India.

This is not the first time that rats have posed a problem to Air India.

A flight to Toronto was delayed for 11 hours in 2009 as staff tried to catch rats.

In another incident in Mumbai last year, officials blamed a short circuit caused by rat excreta for a communications blackout that led to the closure of the city’s secondary airport for three hours.

An investigation into the incident at Juhu airport by the Airports Authority of India said cables linked to the site’s VHF radio system had been chewed through by rats, whose excreta was then thought to have triggered a short circuit.